For several years, various disorders have been reported in two Loire cattle farms: high mortality, lameness of the cows, reduction in the quality and quantity of milk, inflammation of the udders, etc. Breeders place the beginning of the troubles in 2012, at the time of the construction and then the commissioning of a park of eight wind turbines located approximately 700 and 1,500 meters respectively from each farm. Despite numerous investigations carried out on the two farms (veterinary and electrical audits, infrasound and vibration measurements, etc.), the problems persisted. In this context, the ministries responsible for ecology and agriculture contacted ANSES to determine whether these disturbances were attributable to the presence of wind turbines.
A scientific approach adapted to the physical agents generated by wind turbines
ANSES notes that despite the investigations carried out in the two farms, rigorous and documented monitoring of the remedial actions has not been implemented and that a very degraded situation continues to weigh on people and farms. This calls for appropriate accompanying measures.
To carry out the scientific assessment, the group of experts set up by ANSES first identified the different physical agents generated by wind turbines : audible or non-audible sound waves, electromagnetic fields located both at wind turbines and around cables carrying electricity, parasitic currents, vibrations at ground level. The experts did not retain the visual disturbance caused by the wind turbines, because the vision of cattle and their perception of movements are much worse than those of humans.
In the absence of a suitable method to answer the question posed, the experts developed a accountability assessment method disorders adapted to the physical agents in question, drawing inspiration from the assessment practices used for toxicovigilance. This approach takes several criteria into account: the level of exposure of the animals to the physical agent considered, the part of this physical agent attributable to the wind turbines (the latter not being the only possible source of the physical agents considered), the chronology of events, the possibility that the disturbances had other causes, and finally the existence in the scientific literature of data showing a link between the disturbances observed and the presence of wind turbines.
For each problem observed, the possibility that it was caused by one of the physical agents generated by the wind turbines was evaluated. This evaluation was made independently for each of the two farms.
Attribution of unrest to wind turbines highly unlikely
The experts concluded that the imputability to the wind turbines was mostly excluded. With regard to the elements of comparison, neither the information collected from around twenty ANSES counterparts across Europe, including in countries where wind power is more developed, nor the bibliographical analysis reported the existence of problems of this nature.
Concerning the situation of the two farms, for mastitis, the reduction in the quantity and quality of milk, reproductive disorders and mortality, the expert report concludes that “whatever the physical agent considered, the chronology of the disturbances is incompatible with the periods of construction and commissioning of the wind farm”. For other disorders, exposure levels to most physical agents are low and do not differ from those usually encountered in a farm. However, experts have found a level of exposure to eddy currents unusual in the buildings of the two farms, which they consider probably due to their electrical installations. In addition, other unstudied causes could be at the origin of the disorders encountered, such as diseases, breeding practices, etc.
The age of the facts and the fragmented information made the expertise difficult. The Agency therefore recommends establishing a standardized assessment protocol in order to deal with a similar situation encountered on a farm as soon as possible. This should make it possible to find the causes of the disorders in a global way and without preconceptions, by integrating the physical agents as well as the health and livestock management aspects. He will also have to ensure the traceability of the difficulties encountered by the farms.
A special case that cannot be generalized
The results obtained in these two farms are not cannot be extrapolated to other situations. Research and monitoring work would be required to decide on the potential impact of wind turbines on the health and well-being of farm animals. The experts therefore recommend carrying out a “control case” study comparing farms located close to wind turbines or not, or studies on the same site, which would be carried out before and after the installation of wind turbines in their environment. .
Furthermore, since few studies are available on the sensitivity of farm animals to physical agents, research on this subject should be strengthened. Finally, a reporting system A centralized system for adverse effects following the installation of wind turbines could be put in place, similar to what exists for declaring adverse effects of veterinary medicinal products.